Did you actually think that all ITER parts are located at Cadarache, France? Well, no. PRIMA (Padova Research on ITER Megavolt Accelerator) is located in Italy. It will test the neutral beam heating for the world’s largest tokamak to come. All of PRIMA’s components, one of which goes by the name SPIDER, belong to the ITER Organization. Why does it need another complex multinational experiment to finally turn the big tokamak into a success? It is a matter of dimensions.

Representatives of F4E, Thales and RFX standing in front of the SPIDER beam source. Picture: F4E

Representatives of F4E, Thales and RFX standing in front of the SPIDER beam source. Picture: F4E

“The heating injectors need a performance which is magnitudes above current applications”, says Tullio Bonicelli, responsible Project Manager at Fusion for Energy (F4E). Hence, it seems quite appropriate to test them before they will be finalised in the world’s largest fusion experiment.

Negative ion beams

Powerful beams of neutral particles heat the fusion plasma. Usually, positive ions are accelerated and then neutralised before injection. [see also the article about the helicon plasma source on page XX of this issue].
The ITER Neutral Beam system will use negative ion beams, because the efficiency of neutralising positive ions declines heavily as the beam power increases. Such beams have unprecedented energies of one mega-electron volt (MeV) and they are on for a much longer time (up to one hour) than today’s systems. Each of the two injectors that are currently planned for ITER will transmit 16.5 Megawatt of power to the plasma.

To tackle the challenge of unknown heating dimensions, PRIMA comprises two independent test rigs: The negative ion source SPIDER (Source for Production of Ion of Deuterium Extracted from radio frequency plasma) produces hydrogen and deuterium ions and accelerates them up to 100 kilo-electron volt. MITICA (Megavolt ITER Injector Concept and Advancement), a first full-size and full performance ITER injector, accelerates these ions up to 1 MeV.

Teaming up in Europe, India and Japan

Of course, such efforts can’t be done by one country alone. Tullio Bonicelli describes the team work: “F4E provides important funds to activities under the Neutral Beam Test Facility Agreement. EUROfusion member Consorzio RFX and Italy have provided the buildings and some infrastructure as well as contributing, in a substantial way, to the technical and scientific manpower. The Indian and Japanese agencies from F4E, responsible for ITER, are also making their contributions by delivering important components.

ELISE pioneered for ITER

Research carried out at third parties has also played a major role: the German Max Planck Institute for Plasma Physics has been investigating negative ion sources for years. In fact, their heating source in the ELISE (Extraction from a Large Ion Source Experiment) test rig became the prototype for the ITER system. The device in Garching was half the size of the the one planned for ITER. ELISE produces a particle beam with a cross-sectional area of about one square metre.
SPIDER will start spinning during the first half of next year. MITICA is scheduled to follow in 2022. The experiments that will be carried out after the successful launch are needed to fine-tune the present injector design for ITER.

PRIMA is immense and features many mysterious names. ITER‘s Neutral Beam Test Facility in Padova will switch on the light in the first half of 2018. Take a tour through MITICA and SPIDER before they get busy.

Interview with Tullio Bonicelli, Project Manager for Neutral Beam and Electron Cyclotron Power Supplies and Sources at Fusion For Energy

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What is the economic impact on the PRIMA facility for European companies?

Many companies have been involved in our contribution to the PRIMA facility, such as OCEM ET, COELME, Thales, Zanon, CECOM, Galvano-T, Siemens, DILO, De Pretto, NIDEC, Angelantoni, Delta-T and many important sub-contractors such as Himmelwerk, HSP or Andreas Karl. The cumulative value of the contracts that we have signed is in the range of 120 million Euros.

What does it mean to build this large device while cooperating with Consorzio RFX and Domestic Agencies in India and Japan?

In a nutshell, the Neutral Beam Test Facility in Padova is very similar to ITER, from an organisational point of view. Some root issues are therefore also common, like the separation between design authority and financial or contractual responsibilities. The decision-making process may become cumbersome and long, introducing in itself risks of additional delays and costs. The successful execution therefore needs collaboration, a certain degree of flexibility, a lot of pragmatism, and, crucially, the common drive of all partners towards the final objective.

Is there anything F4E has learned for the project management at ITER?

There is one main conclusion to be drawn and that applies to all parties – the principle of collaboration. It pays off in spite the additional interfaces that unfold in the process. We learn to listen to one another, manage the project together because we are responsible for its different components, and last but not least, we get to capitalise on a wide set of skills.

Will ITER, in the end, be flexible enough to adjust to the results found at PRIMA?

Yes. There is full confidence that the present lay-out of ITER’s heating source, will be able to accommodate the modifications coming from the PRIMA test beds.

The entry points of the ITER Neutral Beam Injectors at the second floor of the Bioshield, Tokamak Complex. The picture was taken in December 2016. Picture: F4E

The entry points of the ITER Neutral Beam Injectors at the second floor of the Bioshield, Tokamak Complex. The picture was taken in December 2016. Picture: F4E